The invention generally relates to an apparatus which is used with a moving vehicle to provide an alarm when a radar signal impinges on the vehicle. In particular, the invention relates to such an apparatus in which the alarm is responsive to both radar signals impinging on the vehicle and a signal representative of the speed of the vehicle.
Radar detectors are well known in the prior art. In general, such detectors generally provide an alarm indication when a radar signal is received. Recent developments in radar detectors have focused on the sensitivity of the detectors and the various bandwidths within which radar signals are detected. However, there is a continuing need to improve the accuracy of alarms provided by radar detectors.
Some recent developments have suggested using a radar detector in combination with a speed measuring device and printer for verifying vehicle speed. For example, U.S. Pat. No. 5,510,793, incorporated herein by reference, discloses such a system which enables the user to verify the speed of the vehicle responsive to sensing that a radar device has been used to measure the speed. Other developments, such as U.S. Pat. No. 5,485,161, incorporated herein by reference, disclose a vehicle speed control based on GPS/MAP matching of posted speed limits. This system actually limits the vehicle speed based on its position.
None of these developments address a common problem with many radar detectors, i.e., false alarms. In general, detectors tend to indicate false alarms in response to signals which appear to be but are not radar signals. In addition, radar detectors tend to provide alarms whenever a radar signal is received, even in situations where the vehicle is at rest and no alarm is really necessary. Therefore, there is a need for an apparatus including a radar detector which minimizes false alarms and only provides alarms when necessary.